Refer to specially designed flowcharts to identify issues and find solutions fast

Consolidate VPN troubleshooting knowledge through bonus hands-on labs

Read and understand detailed analysis of all relevant VPN show and debug command output

Troubleshooting Virtual Private Networks presents a systematic troubleshooting methodology for network engineers, administrators, and architects tasked with managing and deploying Cisco IOS VPNs. With eight self-contained chapters designed to facilitate rapid and straightforward troubleshooting, this book provides detailed information on addressing all common and not-so-common issues with IPSec VPNs, MPLS Layer-3 VPNs, Any Transport over MPLS (AToM)-based Layer-2 VPNs, L2TP Version 3 (L2TPv3)-based Layer-2 VPNs, L2TP Version 2 (L2TPv2) VPNs, PPTP VPNs, and L2F VPNs. This book not only shows you how to correct problems but also how to avoid them in the first place with expert VPN configuration guidance and optimization tips.

Each chapter in Troubleshooting Virtual Private Networks includes a step-by-step, end-to-end troubleshooting approach to a different VPN technology. In-depth technical discussions and configuration reviews orient you to the VPN technology and get you ready to work. To help you access the answers you need, you'll find flowcharts in each chapter that provide a roadmap for rapid issue resolution. Solutions to complex or unusual issues can be found in case studies at the end of each chapter, along with review questions that test your knowledge. Bonus troubleshooting labs are also included to help you consolidate the skills learned throughout the book.

Whether you are looking to update or hone your skills, Troubleshooting Virtual Private Networks is your first and last reference for mastering advanced VPN troubleshooting.

This book is part of the Networking Technology Series from Cisco Press¿ which offers networking professionals valuable information for constructing efficient networks, understanding new technologies, and building successful careers.

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Tips

Virtual private networking technologies are many and varied. There are, however, a number of tips that will aid in the troubleshooting all of these technologies.

Baseline your network
Make sure that you baseline the performance of your network. Collect information and statistics such as utilization, latency, and error rates. This will enable you to quickly recognize any issues that crop up on your network.

Know your VPN technology
Fast and efficient troubleshooting of VPN technologies requires a good knowledge of the technologies themselves. It's too late to acquire this knowledge when things go wrong, so make sure you acquire it in advance!

Some VPN technologies such as L2TPv2 require an asymmetrical approach to troubleshooting. In this case, you should begin on the tunnel-initiating device, and methodically troubleshoot tunnel setup to the tunnel-terminating device.

Other VPN technologies such as MPLS require a symmetrical approach to troubleshooting. In this case, you should begin troubleshooting on the ingress provider edge (PE) router (or attached customer edge (CE) router), and methodically troubleshoot to the egress PE router (or connected CE router). You should then begin troubleshooting in the opposite direction.

Understand your troubleshooting tools
Ensure you have a good understanding of the troubleshooting tools available to you.

If you are troubleshooting MPLS VPNs, you'll need to familiarise yourself with the output of the show ip cef, show mpls, and show ip bgp vpnv4 vrf commands, for example.

Make sure you also understand the impact of debug commands on the network device, as well as methods of alleviating their effect. For example, you should consider using the debug condition command to limit the output of certain debug commands.